1. Technical Field
The present invention relates to a technique of controlling an electromechanical device such as a motor or a power generator.
2. Related Art
For example, a motor described in JP-A-2001-298982 has been known.
In the motor, when a voltage applied to a magnet coil is lowered, a rotation speed-torque line moves to a low torque and a low rotation speed. That is, the rotation speed and the output torque are lowered. Accordingly, in order to rotationally drive the motor with a high torque or a high rotation speed, the voltage applied to the magnet coil has to be kept high. Particularly, when the motor is used in a moving machine such as a vehicle, a high voltage is applied to the magnet coil to rotationally drive the motor in a high-speed area, thereby increasing the power consumption of the motor. When the motor is used in a moving machine and is used as a regeneration brake at the time of reducing the speed, the moving machine may be excessively braked. These problems are common to various motors.